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New Studies Reveal Cholesterol and Weight Concerns for Low-Carb Dieters

WASHINGTON—Two new studies published in the May 18, 2004, Annals of Internal Medicine provide bad news for low-carb dieters, say doctors for the Physicians Committee for Responsible Medicine. The first, conducted at Duke University, showed that “bad” (LDL) cholesterol levels rose significantly in 30 percent of low-carbohydrate dieters. The second, conducted at the Philadelphia Veterans Affairs Medical Center, showed that weight lost during low-carb dieting started to return after six months.

Normally, weight loss causes cholesterol levels to fall. However, some low-carb dieters have experienced the opposite effect—significant increases of cholesterol levels. In the Duke University study, two study participants dropped out because of high levels of LDL (“bad”) cholesterol: One had an increase in LDL cholesterol from 182 mg/dl to 219 mg/dl in four weeks; the second had an increase from 184 mg/dl to 283 mg/dl in three months. Normal levels are < 100 mg/dl. A third participant developed chest pain and was subsequently diagnosed with coronary heart disease. In all, 45 people followed the low-carb diet for 6 months. But 30 percent of them had an LDL cholesterol increase of more than 10 percent.

In the Philadelphia study, low-carb dieters lost substantial amounts of weight over the first six months. But after that point, the average weight began to climb so that weight loss after one year (11.2 pounds) was not significantly better than that seen with other diets. Two study participants on the low-carb diet died, one from hyperosmolar coma five months into the study, and the second from severe ischemic cardiomyopathy ten months into the study.

“This new evidence confirms that levels of “bad” cholesterol worsen in a substantial number of low-carbohydrate dieters,” said PCRM President Neal D. Barnard, M.D. “And the supposedly dramatic benefits of the diet do not hold up over the long term.” A 2003 study conducted at the University of Pennsylvania showed that low-carb dieters began to regain lost weight after six months. The new results confirm these findings.

PCRM is urging the Secretary of the Department of Health and Human Services, Tommy Thompson, to convene a panel to investigate the potential adverse effects of low-carbohydrate diets on cholesterol levels, as well as on calcium losses, another problem observed in recent low-carbohydrate diet studies.

Founded in 1985, the Physicians Committee for Responsible Medicine is a nonprofit health organization that promotes preventive medicine, conducts clinical research, and encourages higher standards for ethics and effectiveness in research.